1. Field of the Invention
The invention relates to a heat transfer device. More particularly, the invention relates to a heat transfer device to be used in an exhaust conduit of a semiconductor fabrication device.
2. Description of the Prior Art
Physical vapor deposition (PVD), chemical vapor deposition (CVD), ion implantation, certain etching processes, and certain metal deposition processes are examples of plasma assisted semiconductor fabrication processes. A plasma is initiated and maintained within a semiconductor process chamber by applying a high power electric field to a semiconductor process chamber. The plasma (typically characterized by a visible glow) is a mixture comprising neutrons, electrons, positive ions, and/or negative ions. The plasma either deposits material on, or etches material from, a substrate contained within the semiconductor process chamber. The substrate may be a semiconductor wafer, a light emitting diode (LED) display screen, or any of a variety of known substrates.
Plasmas for substrate processing are generated and sustained under a variety of vacuum, temperature, magnetic, and electric conditions. A variety of gases may be input into the semiconductor process chamber to ignite and maintain the plasma. The process consumes a large percentage, but not all, of the gases and generates an effluent comprising unconsumed gases, consumed gas by-products, and other by-products of the process. Additionally, semiconductor process chambers are provided with multiple exhaust pumps often arranged serially to create the vacuum process environment within the semiconductor process chamber. The multiple exhaust pumps remove the effluent from the semiconductor process chamber. An exhaust conduit extends between the two exhaust pumps. If the gases passing through the exhaust conduit are not at a sufficient temperature, then the unconsumed gases are not completely oxidized (or otherwise converted into an acceptable form) in the exhaust conduit. For example, perfluorocarbons (PFC) are by-products of certain processes. Purely thermal reactions between PFCs such as C2F6, CF4, and C4F8 and oxygen molecules require temperatures below 1500xc2x0 K in the absence of a plasma. A considerable amount of energy must be continually supplied to the exhaust conduit to raise its temperature to a level sufficient to perform such a thermal reaction.
It would be desirable to provide a system by which the exhaust conduit wall and the gasses passing through the exhaust conduit can be heated more rapidly and maintained at a higher temperature to enhance the consumption of unconsumed gasses, or effluents.
Many of the disadvantages associated with the prior art are overcome with the present method and apparatus configured to be disposed within a conduit including a heating element. The heating element generates heat in response to magnetic flux generated by an inductive coil. The heating element comprises a heat liner attached to a plurality of ferromagnetic elements. The heating element may be displaced within the conduit to control the amount of heat generated by the heating element.
The heating element has been found especially applicable in situations where considerable variations exist in the temperature of the interior of a semiconductor process chamber and other process system components (i.e., conduits). Such other components can be heated to more completely consume effluents thereby reducing dangerous process by-products.